Signaling system.



S A. REED. SIGNALING SYSTEM.

APPLICATION FILED 0012a, 1905.

000.1. .5 mm m w n t t n A mm W. Mm m m M a P Attest:

S. A. REED.

SIGNALING SYSTEM. APPLIUATION FILED 001228, 1905.

Patented Jan. 5, 1909. 2 SHEETS-SHEET 2.

SYLVANUS ALBERT REED, OF NEW YORK, N. Y.

SIGNALING SYSTEM.

Specification of Letit'em Patent.

Patented Jan. 5, 1909.

Application filed October 26, 1905. Serial No.'284,477.

To all whom it may-concern:

Be it known that I, SYLVANUS ALBERT REED, a citizen of the United States, residing in the city, county, and State of New York, have invented certain new and useful Improvements in Signaling Systems, of which the following is a full, true, and concise specification.

My invention relates to selective signaling and especially to an arrangement of ground connections for telephone party lines, which will allow circuits to be kept normally conductively discontinuousby means of condcnsers, will maintain a balance and guard against inductive or ground disturbances, will offer across the line an impedance sn fficient to protect the talking circuit, and may be capable of selective signaling.

The principle of the invention and several modes of applying the same are hereinafter fully disclosed and more particularly pointed out in the accompanying claims.

Referring to the accompanying drawing Figure 1 represents an application of the principle of my invention to a two party line using ordinary alternating or pulsating currents for ringing; Fig. 2 an application of the same to a four (4) party line, using biased bells which are adapted to be selectively operated by a current capable of ring ing plus or minus through a condenser; Fig. 3 a modified arrangement of the impedance in a two party line; Fig. 4 represents the same modification applied to a four party line. and Fig. 5 is a detail of a station modification.

Referring to Fig. 1, R-=R are signal receiving annunciators or telephone ringers, R being at station A. and R at station B on a bridge respectively, across the party line M N leading to a central station at which the said line terminates in an ordinary jack J. References m n are the strands of a switchboard cord terminating in the plug P. and a, b, are ringing keys adapted to apply current from alternating current generators Gr and'G in the appropriate manner for selectively ringing R or B respectively. T he bridge at station A is conductively interrupted by the condenser K therein which may conveniently have a capacity of about 2 microfarads, andthe bridge at station B is conductively interrupted by two or more condensers K and K each of about 1 microfaradcapacity. The ringer R of bridge A may conveniently be of about 2,500 ohms resistance. The rin er R is contained in a. ground branch which leads from a point on the bridge B which is so located thereon as that there will be an equal impedance and capacity in each side of it toward the line conductors, or so as to -p'roduce an equalization of disturbing ground currents between the two sides M J of the line, such equalization being conditionedby the location of the grounds as will hereinafter be specified. The resistance of ringer B may conveniently be of about 187 5 ohms. Ringing key a--vvhen operated, connects :generator G in bridge across the strands-of the cordmm, and therefore across the line-M N, and it is evident that R will not be a-fiected by such ringing current, while-R will be so aflectcd. Ringing key b con-meets generator G between the two cord strands m n and the two sides M N of the line in parallel, so that current will traverse the-condensers K, K? in parallo] and the two halves of the impedance 1 in parallel through the ringer R to ground, and it is evident that, provided there is. a balance of conditions in the two parallel branches for the current just named, ringer R will not'be affected bycurrent fromenerator G while ringer R will be so a ected. Current generator G will divide in opposite directions through the halves of coil I, and consequently the impedance of I will be neutralized and the resistance reduced to one quarter, while the joint ca acity of the two condensers K K in mutiple will be double that of each or equal to that of ;K in bridge A. Either ringer may be operated by the depression of the a prop-riatekey and distiiirbance from groan currents is obviate Referring now to Fig. 2-M, N, m the two sides of a party line having four (4-) stations, A A"B B, and terminating in jack 3', at an operating station or exchange, whereby they maybe connected respectively by plug -P to the strands m, n, of a switchboard cord. The selective ringing keys d, a, band 6 are adapted to connect to the line the generators G, G or G in appropriate manner to actuate the ringers R, R, R

" and B respectively. The latter ordinarily each connected in series in their station bridges with condensers K and K of about two microfarads ca acity each, and ringers,

R R are located i ground branches connected to the appropriate balancing point of their respective station bridges. The latter contain impedance and ca'pacity elements as indicated by the coils I, I and the condensers K K, K and K", the said elements being, arranged so that each bridge has its impedance, and its condenser in series on both sides of its said balancing point. The impedance coils have about 2,500 ohms reslstance. The condensers render the sides M, N, conductively'separated. The generators G, G and Gr are specially constructed with reference to the line conditions, to produce a current which will create a ditference of potential between the opposed condenser su-r aces, first abruptly or cumulatively and then gradually or non-cumulatively and vice versa, so that the condenser-affected current which passes into the ringers will be alternately'superior or-inferior in motor effect to the bias tensions thereof and may be reversed at will to causethe superior current to be either of plus or minus polari whereby either of the oppositely biase ringers may be operated: The generator G, when connected to the line by the operation of key a, delivers current to the line conductors M. N, which produces an establishment or disestablishment of a difference of potential be tween the condenser surfaces of K and K in the above manner so that the plus current will be superior and will actuate the armature of R while the minus current is inef-' fectual to overcome the bias tensionof the armature of R. The ringers R and R will obviously be not actuated for the same reasons as explained in connection with Fig. 1.

.Simjlarly when key a is operated, the gento produce in conjunction with the con ens.

ers, a current to which the positively biased ringer R alone is responsive, the same as above explained, and G a current to wh ch the negatively biased ringer R alone is IBSPOl'lSlVQllllS being effected according to the principle of selection above explained. Consequently the operation of key 1; rings selectively the bell at station B--and the operation of key 1) rings selectively the bell at station 13. Current from generators G G will divide in opposite directions through thelialves of the coils I, 1', respectively, and the lnipedances of I, I will be neutralized, while the resistances will. be reduced one quarter, and the joint capacity of the two is shown included at station B in a bridge p across the line. Provided there are no other grounds but those specified and that the impedances are equal in the bridge for each side of the ground connection, it will be free from disturbances due to varying'potential clifierence at the ground connections of the circuit, on account of the fact that such disturbing current will divide equally between the two sides of the line in parallel, and in addition will pass with difliculty through the impedances of the grounded ringers. The same conditions obtain in Fig. 2. The impedances I, 1 protect. the talking circuit from short circiiit in the same manner as the ringers R, R so protect the talking circuit. In fact the protection will be better, on account of the fact that the capacities of the two condensers K, K (Fig. l) in series is half the capacity of each singly and the same is true in Big. 2 of the two condensers K 1' in'series, or the two condensers K, K in series.

Certain telephone switchboard circuits include a ground branch at some point which cannot be conveniently disconnected during ringing. Such a ground branch may deflect a part of the ringing current when ringing across the line as described with relation to Figs. 1 and 2, so that part of the current would pass through the grounded ringers and thus vitiate the selection. Figs. 3' and 4 exhibit a modification of the grounded ringer circuits to meet such a continge cy. The permanent ground branch in these circuits is shown at C (Figs. 3 and i} in the form of a cut-all relay connected to one side N, of the jack J, and the adaptation of the circuit consists in constituting the ringer R (Fig. 3 as a part of .the impedance. That is to say, the ground branc at station B leads to a balancing point which is located between. the impedance of the ringer on one side and the impedance of coil 1* on the ot er, condensers being included in the sta' tw r ge as in t e cases first described. The r nger R is on that side of the balancing point which is not grounded by the cut-ott' relay.

The ringing generator G is grounded on one side and in the case of key 6 of Fig. 3, the operation of the key grounds the side, M, of the line at the same time that the side N connects to the grounded generator, the side to be grounded 1. .lng in every case that in which "the rim ers in the impedance bridges are place The effect of this ground at key b is to short circuit the ringer R so that current from G will reach N through the impedance I and leave the ringer R silent. Ringer R will, however,

respond as it will be in a branch of the maincircuit established by the key and its share of the ringing current will depend upon the resistance of I which may be made sufiicient to divert the necessary ringing current to R. Rin er R" is rung by the operation of key a which connects both sides of the line to one pole of the generator, the other pole being grounded, thereb causing a current to travel through both sldes of the line in par 'allel to the condensers K and K in parallel,

and through the ringer R in parallel with the coil I, to ground. Ringer R will be unaffected by the current for obvious reasons.

Carrying the same principle of arrangement to the four party line ofFig. 4, R, R are oppositely biased ringers in two bridges, broken by condensers K. and K respectively. R and R are similar ringers in line bridges which are respectively interrupted as to their conductive continuity by condensers K K? and K, K respectively, the said ringers being each located in the bridge on the opposite side of the ground connection from the impedance coils I I respectively; and on that side of the said point which is not grounded by the cut-off relay C. The generators G, G are appropriately connected with the keys at, a, b, b and with round to produce a selective actuation of t e ringers at the several stations according to the key which is operated, exactly as in the case described with reference to Fig. 2 but with the protection against the ground in line N through the relay C, as has been described with reference to Fig. 3. The operation will be apparent from an examination of the circuit without tracing the several paths. The telephone talking apparatus for this modified form of system may be applied as shown in Fig. 3 so that it will be connected in bridge across the line and interrupt the ground connection wh in use, but will close such connection when not in use. The same talking apparatus can obviously be applied to the stations of Fig. 4. In each of the foregoing cases. it will be e ident that the relative positions of t. impedance and capacity elements maybe reversed; without vitiating the conditions of uccessful operation. Such an arrangement is illustrated for convenience in Fig.5. I.

do not confine myself to'the speci wide! of ance across line to talking from the middle point is familiar in the art as a means of attaining two non-interfering circuits, but the adjustment to a balance to eliminate the effect of ground disturbances to voice currents is a novel and important feature which I wish to be understood as 35 claiming herein.

Having described my inven ion, wha claim and desire to secure by UnitedStatt Letters Patent is:

1. In a signaling system, a party line having a pair of bridges thereacross, branches to ground from said bridges, and impedance elements and condensers in each bridge located therein on each side of the ground branches thereof and adjusted to divert ground currents equally to both sides of the line, in combination with a pair ofv oppositely i used annunciator elements respec tively connected with each bridge and adapted to be operated by current of r propriate direction passing through 11. ground branch, and a source of current adapted to be connected with both sides of the line and ground, and to produce a current which will alternately change the potential difierence of the bridge condensers abruptly and gradually or vice versa, whereby the condenser afi'nited ct -"rent will be alternately superior and inferior in motor effect to the bias tensions of said annunciator element.

2. In a selective foui party signaling line, two bridges thereacrosacontaining respectively oppositely biased ringers and condensers 111 series therewith, two other bridges each connected with ground and containing condensers andimpedance elements on each side of i grounded points, adjusted to divert gromid curre s equally to both sides of the line, and c positely biased ringers respectively associe ed with each said last named bridges to be operated by appropriate current passing through the ground branches thereof, in combination with means of-irnpressing current on the line to charge the condensers alternately. abruptly and gradually or vice versa, and switches for passin said current through said first name bridges in series with the sicies of the line, name to the specification in the presence of or through the last named brldges and both two subscribing witnesses. sides of the line in multiple and through 7 T grpungi, the condenser affected current in LVABUS ALBERT REED 5 stud rm ers being alternately superior and \Vitnesses:

inferior mmotor effect to their bias tensions. G. A. TAYLOR,

In testimony whereof, I have signed my H. G. KIMBALL. 

